He joined the Tulane Law faculty as director of the Law Library and Associate Professor of Law in 2008 after 20 years with the Southern Illinois University School of Law, where he held numerous positions at the law library and taught Advanced Electronic Legal Research, Computers and the Law, Legal Research and Lawyering Skills.

His long involvement with the American Association of Law Libraries includes serving as president in 2008-2009. He was inducted into the AALL Hall of Fame in 2014.

Duggan is editor of the Law Library Journal and is a past chair of the Association of American Law Schools Section on Law Libraries and Legal Information. He has had articles published on topics including legal research, legal issues related to computers, the internet and technology. He also chairs the Louisiana Academic Libraries Information Network Consortium (LALINC) Executive Board.